feat: support off-shelf location registration

app/services/location_service.py

@@ -1,3 +1,5 @@
+from datetime import datetime
+
 from sqlalchemy.orm import Session
 
 from app.models.finished_goods import FinishedGoodsLocation
@@ -12,6 +14,18 @@ class DuplicateLocationError(Exception):
         self.registered_at = registered_at
 
 
+class AlreadyOffShelfError(Exception):
+    """总排号已下架至转运区域。"""
+
+    def __init__(self, location_code: str, registered_at: str):
+        self.location_code = location_code
+        self.registered_at = registered_at
+
+
+def _is_transit_location(location_code: str) -> bool:
+    return location_code.startswith("TRANS-")
+
+
 def register_location(db: Session, req: LocationRequest) -> FinishedGoodsLocation:
     existing = (
         db.query(FinishedGoodsLocation)
@@ -19,6 +33,21 @@ def register_location(db: Session, req: LocationRequest) -> FinishedGoodsLocatio
         .first()
     )
     if existing:
+        if _is_transit_location(existing.location_code):
+            raise AlreadyOffShelfError(
+                location_code=existing.location_code,
+                registered_at=existing.created_at.isoformat(),
+            )
+
+        if _is_transit_location(req.location_code):
+            previous_location = existing.location_code
+            existing.location_code = req.location_code
+            existing.created_at = datetime.now()
+            db.commit()
+            db.refresh(existing)
+            existing.previous_location = previous_location
+            return existing
+
         raise DuplicateLocationError(
             location_code=existing.location_code,
             registered_at=existing.created_at.isoformat(),